farmOS/modules/farm/farm_ledger/farm_ledger.module

<?php
/**
 * @file
 * Code for the Farm Ledger feature.
 */

include_once 'farm_ledger.features.inc';

/**
 * Implements hook_farm_ui_entities().
 */
function farm_ledger_farm_ui_entities() {
  return array(
    'log' => array(
      'farm_purchase' => array(
        'label' => t('Purchase'),
        'label_plural' => t('Purchases'),
        'view' => 'farm_log_purchase',
        'weight' => 90,
      ),
      'farm_sale' => array(
        'label' => t('Sale'),
        'label_plural' => t('Sales'),
        'view' => 'farm_log_sale',
        'weight' => 90,
      ),
    ),
  );
}

/**
 * Implements hook_feeds_importer_default_alter().
 */
function farm_ledger_feeds_importer_default_alter(&$importers) {

  // Add extra field mappings to sales.
  $name = 'log_farm_sale';
  if (!empty($importers[$name])) {
    $mappings = array(
      array(
        'source' => 'Customer',
        'target' => 'field_farm_customer',
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Invoice number',
        'target' => 'field_farm_invoice_number',
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Lot number',
        'target' => 'field_farm_lot_number',
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Quantity',
        'target' => 'field_farm_quantity_value',
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Units',
        'target' => 'field_farm_quantity_units',
        'term_search' => '0',
        'autocreate' => 1,
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Unit price',
        'target' => 'field_farm_unit_price',
        'unique' => FALSE,
        'language' => 'und',
      ),
      array(
        'source' => 'Total price',
        'target' => 'field_farm_total_price',
        'unique' => FALSE,
        'language' => 'und',
      ),
    );
    $importer_mappings =& $importers[$name]->config['processor']['config']['mappings'];
    $importer_mappings = array_merge($importer_mappings, $mappings);
  }
}